Pacific jumping mice can be distinguished from other rodents that belong to the same genus by their larger size. They have a distinct color separation between the back and underside. See reference for further detailed anatomical information. These rodents prefer to live in moist habitats, and are frequently found in riparian or meadow areas near rivulets. They rely on grass seeds as their main diet, thus they prefer inhabiting areas with thick vegetation, which provide refuge from many predators as well as food resources. Besides eating grass, they feed also on fungi and insects. They spend most of the autumn season fattening up in preparation for their winter hibernation time, which is spent in small burrows in the ground. When their hibernating period of up to 8 months is over, they mate and produce a litter of four or more young. Pacific jumping mice have many predators, including snakes, coyotes, owls, and foxes.
Distribution
Pacific jumping mice prefer living in moist regions that are characterized by alder / salmonberry / skunk-cabbage marsh, and riparian alder ecosystems that are commonly found in coastal redwood woodlands. In northern regions they dwell in dense woodlands, wet grassy regions, and alpine meadows of the Cascade Mountains in Washington and Olympic peninsula. They can be found in marshy thickets, woodlands edges that contain both weedy understory and ferns, and in moist meadows.
Habitat
The habitat of Pacific jumping mice includes streams, brushlands, lakes, woodlands, forests, fields, swamps, meadows, shrubs, bogs, marshes, and the banks of rivers and ponds. Their range covers the entire Pacific Northwest, California, and western Canada.
Diet
Food items for Pacific jumping mice include fungi, fish, insects, mollusks, wild fruits, seeds, and wild berries. They forage for food material at ground level, and will cut down tall plant stems in order to reach the seeds, and will cut grass and leave it in an orderly pile. They do not store food. The dental formula of Zapus trinotatus is = 18.
Behavior
Their infants make a sharp squeal. Mature Pacific jumping mice evade their predators by leaping distances of over 150 cm; they leap with their head turned downwards, arching their back and diving on the ground, and at the same time preparing to make another leap. They may also evade predation by remaining motionless, and depending on their camouflage effect. They are most active from dusk until dawn. They feed by seizing food with their forepaws. Their behavior is typically nervous and high-strung, and they can be aggressive when trapped. However, despite showing some signs of aggressiveness, the Pacific jumping mouse is naturally gentle. When they engage in fighting, they produce a characteristic squeaking noise and at the same time pulsate their tail against the substrate and thus produce a drumming noise. When this rodent is agitated, it jumps and moves madly from one place to another. Pacific jumping mice prepare for summer by constructing a domed-shaped, fragile nest with a single entrance, usually placed on the ground.
Reproduction
Pacific jumping mouse sexually mature the year after they are born. Males become sexually active in May or June, which is when females are also fertile. Their gestation period lasts about 18–23 days and give birth in July or August. Each litter consist of about 4-8 young, which are weaned after 4 weeks. The Pacific jumping mouse are born pink and hairless, and weigh around 0.7 - 0.9 grams at birth. They are also born with their eyes shut and depend on their mother to survive the first few weeks. They become independent after about a month.
Genetic makeup
The genetic makeup of a given population of Pacific jumping mice depends on their mating system, characteristics of the species, demography, and dispersal. However the following three components seem to be important to the genetic health of the Pacific jumping mouse. The first component is behavioral instigation of dispersal. The second component is the significance of species dispersal as an initiator of migrating patterns that also include mating selections. The third component is the impact of dispersion on gender-specific models of species relatedness, and thus, on allelic allotment within the population.
